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Estimation
Addition
Subtraction
Rounding
Word Problems
100
Use estimation to answer the following problem: 27 + 39
30 + 40 = 70
100
394 + 254
648
100
488 - 24
464
100
Round 457 to the nearest 10
460
100

The cost of an apple is 39 cents. Robert had 25 cents in his pocket. How much more money did Robert need to purchase the apple?

14 cents more

200
Use estimation to answer the following problem: 49 - 31
50 - 30 = 20
200
702 + 699
1401
200
23,921 - 1,399
22,522
200
Round 4,651 to the nearest 100
4,700
200

Volunteer teams identified 73 fish species, 30 corals, and 71 other invertebrates on the reef. How many species of fish, coral, and invertebrates were found in all?

174 species

300
Use estimation to answer the following problem: 89 + 47 =
90 + 50 = 140
300
24,945 + 9,466
34,411
300
40,502 - 12,999
27,503
300
Round 45,250 to the nearest 1,000
45,000
300

Sandy read 235 pages of a book. She had 192 more pages to read before she was done. How many pages were there in the book? Write and solve an equation. 

235 + 192 = 427

427 pages in all. 

400
Use estimation to answer the following problem: 121 - 103 =
120 - 100 = 20
400
78,999 + 21,888
100,887
400
100,100 - 99,999
101
400
Round 3,599 to the nearest thousand
4,000
400

The population of New City is 23,945 people. Eastdale has a population of 12,774 people. What is the total population of the two communities? Write and solve an equation. 

23,945 + 12,774 = 36,719

36,719 people.

500
Use estimation to answer the following problem: 27,982 + 12,444
30,000 + 10,000 = 40,000
500
99,999 + 99,999
199,998
500
205,010 - 87,255
117,755
500
Round 34,954 to the nearest ten, hundred, and thousand.
Ten: 34,950 Hundred: 35,000 Thousand: 35,000
500

Mike's team scored 63 points in the first half of a basketball game. His team won the game by a score of 124 to 103. How many points did his team score in the second half? Write and solve an equation. 

124 - 63 = 61

61 points